Sewing machine cooling system

ABSTRACT

A sewing machine is provided with a ducted fan mounted on the machine drive shaft. The fan provides a substantially axial flow. Air discharged from the fan is directed over the bottom cover plate of the sewing machine which is provided with heat dissipating fins. Additionally, air discharged from the fan is directed over the top of the machine.

United States Patent [191 Tranquilla et al.

[ Nov. 13, 1973 SEWING MACHINE COOLING SYSTEM Inventors: Michael N.Tranquilla, Elmhurst;

Gerald A. Kraatz, Highland Park, both of I11.

Assignee: Union Special Corporation, Chicago,

Filed: June 28, 1972 Appl. No.: 267,134

US. Cl. 112/218 R, 112/256 Int. Cl D05b 71/00 Field of Search 112/218 R,256;

References Cited UNITED STATES PATENTS 2/1972 Armstead et al. 112/2183,081,723 3/1963 Kostenowczyk 112/256 2,144,326 l/1939 Callighan 112/218R 1,844,743 2/1932 Christensen 112/218 R Primary Examiner-H. HamptonHunter Attorney-John A. Howson et a1.

[5 7} ABSTRACT A sewing machine is provided with a ducted fan mounted onthe machine drive shaft. The fan provides a substantially axial flow.Air discharged from the fan is directed over the bottom cover plate ofthe sewing machine which is provided with heat dissipating fins.Additionally, air discharged from the fan is directed over the top ofthe machine.

15 Claims, 5 Drawing Figures PAIENIEDRBY 13 ms 3,771,478

SHEET 2 GF 4 FIG. 2

PAIENTEUHUV 13 1915 SHEET UF 4 SEWING MACHINE COOLING SYSTEM BACKGROUNDOF THE INVENTION 1. Field to Which the Invention Pertains This inventionpertains to sewing machines and particularly to a cooling system for asewing machine.

Sewing machines, particularly industrial sewing machines, often operateat extremely high speeds, e.g., industrial sewing machines are availablewhich run at speeds as high as 8,000 rpm. Since such machines employnumerous mechanical parts which are in moving contact, sophisticatedlubrication systems are necessitated. Notwithstanding the sophisticationof these lubrication systems, a substantial amount of heat is generatedwhen the various mechanical parts of the sewing machine operate at suchhigh speeds. Generally, such frictionally generated heat is manifestedby an increase in both the temperature of the oil and the temperature ofthe various mechanical parts and frame which comprise the machine. For anumber of reasons, it is important that some of this heat is dissipated.For example, if a cooling system is not provided to dissipate some ofthis heat, the lubricating oil may suffer a thermal degradation with theresult that the required lubrication will not be provided. Additionally,the temperature of the exterior members of the sewing machine must belimited in order to insure both the safety and comfort of the operator.

A novel cooling system for dissipating such frictionally generated heatis the field to which this invention pertains.

2. Prior Art The prior art has recognized the need for providing acooling system for a sewing machine and particularly the need forproviding a cooling system in conjunction with high speed, industrialsewing machines. Thus, various sewing machine constructions andapparatus arrangements have heretofore been proposed for providing acooling or heat dissipating effect. Exemplary of such prior artconstructions are the cooling systems shown in US. Pat. Nos. 3,638,594;2,678,013; 2,744,482; 3,081,723; 2,222,016; 3,009,430 and 2,711,146.

A common expedient disclosed in some of the aforementioned patents areused by the prior art to dissipate heat generated in a sewing machinecomprises the use of heat dissipating fins exteriorally mounted on asewing machine, for example on the base thereof. Another approachemployed by the prior art to provide heat dissipating effects resides inthe utilization of a fan for creating air flows within or around thesewing machine. Although these and other prior art constructionsprovided a degree of cooling or heat dissipation, it has been found thatprior art cooling systems are not sufficiently effective when employedin combination with sewing machines operating at speeds on the order of7,000 to 8,000 rpm. Thus, at such speeds, the lubricating oil within themachine and the external frame members are heated to undesirably hightemperatures notwithstanding the use of prior art cooling systems.However, through the use of the cooling system disclosed herein, it hasbeen found that the temperature of the lubricating oil and thetemperature of the external members of the machine may be significantlyreduced.

SUMMARY OF THE INVENTION In combination with a sewing machine having amain chamber wherein there is located the mechanical parts for operatingthe machine, there is provided a second chamber adjacent to the machinechamber at one end of the machine. The machine drive shaft extendsthrough both the machine chamber and the second chamber and is providedwith means adapted for external drive, e.g., a pulley mounted on the endof the drive shaft exteriorally of the machine. Mounted on the driveshaft in the second chamber is a ducted fan which provides asubstantially axial flow.

In the preferred embodiment of the invention, the second chamber isprovided with an air inlet port and two discharge ports, one at the topof the second chamber and one at the bottom of the second chamber. Airwhich is axially discharged from the fan is directed downwardly, bylouvers, to the bottom discharge port. Located at the bottom dischargeport is a horizontally disposed louver which redirects the downwardlyflowing air to a horizontal path. Air discharged from the second louverflows along and between heat dissipating fins which are mounted on thebottom cover plate of the machine and disposed longitudinally thereof.

Air from the ducted fan may also be directed along and over the top ofthe machine. In the preferred embodiment of the invention, air flow overthe top of the machine is achieved by providing a slot in the top of theduct associated with the ducted fan. A portion of the air handled by thefan is discharged through the aforementioned slot which is locatedadjacent to the top discharge port in the second chamber. To insure thatair flowing through the top discharge port is conducted over the top ofthe machine, a top cover is provided in the preferred embodiment whichdefines a sealed chamber with respect to the top of the machine. The topcover is provided with slots, preferably at the rear thereof, throughwhich air may be discharged.

To obtain optimum cooling, means are provided adjacent to the bottom ofthe heat dissipating fins for maintaining the air flow between the fins.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view, partially insection, of a sewing machine and showing a preferred embodiment of theinvention.

FIG. 2 is a side view, partially in section, taken along the sectionline 22 of FIG. 1.

FIG. 3 is a side view, partially in section, taken along the sectionline 3-3 of FIG. 1.

FIG. 4 is a fragmentary, bottom view of the sewing machine shown in FIG.1.

FIG. 5 is a view in perspective of certain parts of the sewing machineshown in FIG. 1, said parts being shown in spaced, disassembledarrangement.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION Referring toFIG. 1, there is shown a sewing machine of the over-edge type. Themachine includes an upstanding frame 10 which defines a machine chamber9 and a second chamber 21. Bolted to the upstanding frame 10 is an upperframe 11. The machine chamber 9 is sealed at the top by a top oil coverplate 13 appropriately bolted to the upper frame 11. Mounted on theupper frame 11 is an operating head 12. Affixed to the lower portion ofthe frame 10 is an operating table 12a. The machine chamber 9 is sealedat the bottom by a bottom cover plate 15. As an integral part of thebottom cover plate 15, there are provided a plurality of heatdissipating fins 16 longitudinally disposed along the bottom of thebottom cover plate 15 as most clearly seen in FIGS. 2 and 3. Referringagain to FIG. 1, a drive shaft 19 is mounted on the frame longitudinallythereof and is appropriately journaled for rotation. The drive shaft 19extends through the machine chamber 9 and the second chamber 21 andextends beyond the frame 10, at the right side thereof, where it isadapted for external drive, i.e., the drive shaft 19 is provided with apulley 20. Those skilled in the art willappreciate that within themachine chamber 9 there is located the various mechanical means forproviding an operative connection between the drive shaft 19 and theoperating head 12 as well as the operating table. 12a. Similarly, itwill be appreciated that when a machine such as the one shown in FIG. 1is in operation, a reservoir of lubricating oil 60 (shown in FIG. 1) isprovided for lubricating the mechanical parts which provide theoperative connection between the drive shaft 19 and the operating head12. Typically, various means are provided, and are well known to thoseskilled in the art, to cause oil from the reservoir to be deposited uponthe various mechanical parts mounted within the machine chamber 9. Thus,in operation, the environment defined by the machine chamber 9 will beheated and the oil which drips off the moving parts will be deposited atthe bottom of the machine chamber 9. Hence, for

purposes of description, it will be assumed that the oil reservoir 60and the surfaces which define the machine chamber 9, e.g., the top oilcover plate 13, are at an elevated temperature.

Referring to the second chamber 21, it will be observed that there isprovided an inlet port 46 and two discharge ports, viz a top dischargeport 43 and a bottom discharge port 59. Within the second chamber 21, afan 24 is provided and is constructed so as to provide a substantiallyaxial flow. Additionally, it will be observed that fan 24 is a ductedfan, i.e., referring to FIG. 3, a duct peripherally surrounds the fan24. Referring to FIGS. 1 and 5, it will be seen that the duct whichperipherally surrounds the fan 24 is comprised of a top duct 26 and abottom duct 27. The top duct includes an inverted L shaped plate 31provided with screw receiving slots 23 on the horizontal surfacethereof. Thus, the entire upper duct assembly 25a is maintained inposition within the chamber 21 by affixation to the frame 10, forexample by the use of bolts 33 as shown in FIG. 1. As seen in FIG. 5,the plate 28 includes a plurality of downwardly facing louvers 29. Theplate 29 is affixed to the plate 31, for example by welding.

Similar to the construction of the upper duct assembly 25a the lowerduct 27 includes an L-shaped plate 37 provided with bolt receiving slots22. In this manner, the lower duct assembly 25b may be secured withinthe second chamber 21 (as shown in FIGS. 1 and 2) by screws 38.Referring again to FIG. 5, the plate 34 includes a plurality ofdownwardly facing louvers 35. Plate 34 is fixedly mounted on the plate37, for example by welding. For added strength, support pins and 36 maybe provided for louvers 29, 35, respectively.

It will be noted that the terminal edges 30b of the bottom duct 27 arecrimped for engagement with the terminal edges 30a of the upper duct25a.

Referring to FIGS. 1, 4 and 5, it will be seen that there is provided ahorizontally disposed louver 42 which is affixed by screws 41 to plate39, plate 39 being affixed to the frame 10 by screws 40. As best seen inFIG. 1, the louver 42 terminates adjacent to the transverse edges of thelongitudinally disposed fins 16.

Referring to FIGS. 1 and 3, top cover plate 14 is mounted on the frame10 and together with the top oil cover plate 13 provides a substantiallysealed chamber 61. It will be noted that the substantially sealedchamber 61.is in fluid communication with the second chamber 21 via thetop discharge port 43. Additionally, it will be noted that the top coverplate 14 is provided with a plurality of slots 45 at the rear thereof.

Referring again to FIGS. 1 and 5, it may be observed that a slot 32 isprovided in the top portion of the upper duct 26 and. is located(FIG. 1) adjacent to the top discharge port 43.

When the sewing machine of FIG. 1 is operated, a belt is disposed aboutthe pulley 20 and connected to an electric motor which supplies thenecessary power to rotate the drive shaft 19. Rotation of the main driveshaft 19 rotates the fan 24 which inducts air into the second chamber 21through the intake port 46. Because of the presence of fan duct 26, 27and because the fan 24 is substantially an axial flow fan, thepreponderance of the air conducted into he chamber 21 is axiallydischarged and thus directed against the downwardly facing louver 29,35. Thus, the air axially discharged from the fan 24 is directeddownwardly through the left hand side of the second chamber 21 towardsthe bottom discharge port 59, where it encounters the horizontallydisposed louver 42 and is thus redirected into a horizontal flow betweenthe longitudinally disposed fins 16.

Although the fan 24 provides a substantially axial flow, a radial flowcomponent is nevertheless imparted to some of the air which is handledby the fan 24. Thus, a radial pressure head is developed which causesair to flow through the slot 32 and then through the adjacently disposedtop discharge port 43. In this manner, an air flow is maintained intothe substantially sealed chamber 61. Air flowing into this substantiallysealed chamber 61 passes over the top oil cover plate 13 and isultimately discharged through the slots 45 in the rear 44 of the topcover plate 14.

Returning to a consideration of the air flowing along and between thefins 16 from the bottom discharge port 59 and the louver 42, it has beenfound that this air flow may tend to dissipate downward and around thefins 15 so as to flow transversely thereof. Such cross flows impair theheat transfer efficiency of the cooling fins 16. Thus, it is preferableto provide means for maintaining the air flow between the fins 16. Oneapproach for achieving this objective is to mount a cover plate on thebottom of the fins 16. An-alternate approach, shown in FIG. 1, residesin appropriately sizing the feet 51 which are interposed between thebottom of the machine and surface 50 upon which the machine is mounted.Through the expedient of providing appropriately sized feet, the bottomof the fins 16 may be maintained at an appropriated distance from themounting surface 50. Experiments conducted upon the occasion of thisinvention have indicated that the distance between the bottom of thefins 16 and the mounting surface should not be greater thanapproximately one-eighth of an inch and should preferably beapproximately onesixteenth if the air flow between the fins is to bemaintained.

To determine the effectiveness of the invention hereinbefore described,a high speed, industrial sewing machine was constructed and providedwith the cooling system described above. When operated at a speed of8,000 rpm, the overall machine temperature was reduced by approximatelypercent as compared to a similar machine operating at the same speed butnot provided with this type of cooling system. In other experiments,machines adapted with the cooling system described herein and operatedat speeds of 8,000 rpm were maintained at the same temperature assimilar machines operated at only 7,000 rpm but not provided with theabove described cooling system.

It is believed that a number of factors intrinsic in the design of theinstant cooling system cooperatively interact to provide the superiorheat dissipating effects which have been observed. For example, the useof a ducted fan as opposed to an unducted fan is believed to contributesignificantly to the air handling efficiency of the fan. Similarly,because the fan provides a substantially axial flow and because of thelouvers associated with the fan, it is believed that energy dissipatingvortices are avoided and, as a result, a major portion of the energyexpended for rotating the fan is converted into usable air flow.

Still another factor which is believed to be significant resides inproviding a construction whereby both the top and bottom of the machineis cooled. In this connection, it is significant to note that theconstruction of the instant invention functions to insure that a majorportion of the air handled by the fan is discharged over and along thebottom of the machine. Thus, as compared to the air which flows over thebottom of the machine, a smaller portion of air handled by the fan flowsover the top of the machine. Controlling the two air flows in thismanner is believed to be of significance for the following reasons.Considering a sewing machine of the type shown in FIG. 1, it hashereinbefore been noted that when in operation, the oil reservoir 60will be at an elevated temperature. Similarly, the environment withinthe machine chamber 9 will be at an elevated temperature thus heatingthe top oil cover plate 13. However, comparing the oil reservoir 60 tothe remainder of environment within the machine chamber 9, it will beappreciated that the oil in the reservoir 60 has a significantly higherspecific heat than the air which substantially fills the machine chamber9. Thus, to reduce the temperature of the oil 60 by a given amount, moreheat will have to be transferred therefrom than would have to betransferred from the air in the machine chamber 9 in order to lower thetemperature of the air by the same amount. Thus, by utilizing theinstant invention, a higher cooling air flow is provided with respect tothe oil reservoir 60 than with respect to the top oil cover plate 13.

Another feature of the instant invention which would appear todifferentiate it in effectiveness from the prior art resides in the factthat the air directed from the fan to the fins is cool air which isheated as the air flows along and between the fins. Thus, in fluiddynamic terms, the air flow between the fins would appear to be Rayleighline flow which is characterized by a continuous increase in velocitydue to heat transferred to the air. As the air flows along and betweenthe fins, it is heated and the air expands. Because of the expansion ofthe air, the velocity of the flowing air is increased. By confining theair flow within the fins, by the tableboard or a cover, the increase invelocity of the air flow results in a greater dissipation of heat thanin prior art systems where the air flow was not confined, by some means,to flowing along the fins. Similarly, prior art systems which directedan air flow perpendicularly or obliquely to heat dissipating fins wouldnot possess the above described attributes of the instant coolingsystem.

Although there has hereinbefore described, by way of example, apreferred embodiment of the instant invention, it will be appreciatedthat changes in the specific structure thereof may be made by thoseskilled in the art to which this invention pertains without,nevertheless, departing from the scope of the invention as defined bythe claims appended hereto.

We claim:

1. A sewing machine which comprises:

a. an up-standing frame defining a machine chamber and a second chamberadjacent to said machine chamber at one end of said machine, said secondchamber having an inlet port and at least one discharge port;

b. an operating head mounted on said frame at the other end of saidmachine;

c. a top oil cover plate mounted on the top of said frame and sealingthe top of said machine chamber;

d. a bottom cover plate mounted on said frame and sealing the bottom ofsaid machine chamber;

e. a plurality of heat dissipating fins mounted on the bottom of saidbottom cover plate and extending longitudinally thereof;

f. a drive shaft mounted on said frame longitudinally thereof, extendingthrough said machine chamber and said second chamber and adapted forexternal drive;

g. means within said machine chamber for operatively connecting saiddrive shaft to said operating head;

h. a ducted fan mounted within said second chamber and on said driveshaft for rotation therewith; and

i. means for directing air discharged from said fan along said fins.

2. The sewing machine of claim 1 wherein said heat dissipating fins arean integral part of said bottom cover plate.

3. The sewing machine of claim 2 which further includes means fordirecting air discharged from said fan over said top oil cover plate.

4. The sewing machine of claim 3 which further comprises air flowmaintaining means for maintaining the air flow between said fins.

5. The sewing machine of claim 4 wherein said means for directing airover said top oil cover plate includes means for restricting the airflow over said top oil cover plate such that less air flows over saidtop oil cover plate than along said fins.

6. The sewing machine of claim 5 wherein said air flow maintaining meansis a plate mounted on the bottom of said fins.

7. The sewing machine of claim 5 wherein said air flow maintaining meanscomprises mounting means for maintaining the bottom of said finsadjacent to the surface on which said machine is mounted.

8. The sewing machine of claim 5 wherein said means for directing airoversaid top oil cover plate includes a top cover plate mounted on saidframe above said top oil cover plate, defining a channel therebetweenwhich is in fluid communication with said second chamber, and on saiddrive shaft for rotation therewith; said top plate including at leastone air discharge slot. j. means for directing air from said ducted fan,

9. A sewing machine which comprises: i. through said top port, and

a. an up-standing frame defining a machine chamber ii. through saidbottom port and along said fins.

and a second chamber adjacent to said machine 10. The sewing machine ofclaim 9 wherein said chamber at one end of said machine, said secondmeans for discharging air from said fan through said chamber having aninlet port, a bottom discharge top port comprises a fan duct having aslot in the top port and a top discharge port; portion thereof adjacentsaid top discharge port.

b. an operating head mounted on said frame at the .11. The sewingmachine of claim 10 wherein said other end of said machine; 10 means fordirecting air from said fan along said fins c. a top oil cover platemounted on the top of said comprises:

frame and sealing the top of said machine chamber; a. a plurality ofdownwardly facing louvers mounted d. a top cover plate, having at leastone air discharge on said duct adjacent to the axial discharge of saidslot, mounted on said frame over said top oil cover fan; and plateforming a sealed chamber with said top oil b. a horizontally disposedlouver mounted on said cover plate, said sealed chamber being in fluidframe adjacent to the bottom discharge port. communciation with said topdischarge port; 12. The sewing machine of claim 11 wherein said e. abottom cover plate mounted on said frame and heat dissipating fins arean integral part of said bottom sealing the bottom of said machinechamber; cover plate.

f. a plurality of heat dissipating fins mounted on the 13. The sewingmachine of claim 12 which further bottom of said bottom cover plate andextending comprises air flow maintaining means for maintaininglongitudinally thereof; the air flow between said fins.

g. a drive shaft mounted on said frame longitudinally 14. The sewingmachine of claim 13 wherein said air thereof, extending through saidmachine chamber flow maintaining means is a plate mounted on the botandsaid second chamber and adapted for external tom of said fins. drive;15. The sewing machine of claim 13 wherein said air h. means within saidmachine chamber for opera flow maintaining means comprises mountingmeans for tively connecting said drive shaft to said operatingmaintaining the bottom of said fins adjacent to the surhead; face onwhich said machine is mounted.

i. a ducted fan mounted within said second chamber

1. A sewing machine which comprises: a. an up-standing frame defining amachine chamber and a second chamber adjacent to said machine chamber atone end of said machine, said second chamber having an inlet port and atleast one discharge port; b. an operating head mounted on said frame atthe other end of said machine; c. a top oil cover plate mounted on thetop of said frame and sealing the top of said machine chamber; d. abottom cover plate mounted on said frame and sealing the bottom of saidmachine chamber; e. a plurality of heat dissipating fins mounted on thebottom of said bottom cover plate and extending longitudinally thereof;f. a drive shaft mounted on said frame longitudinally thereof, extendingthrough said machine chamber and said second chamber and adapted forexternal drive; g. means within said machine chamber for operativelyconnecting said drive shaft to said operating head; h. a ducted fanmounted within said second chamber and on said drive shaft for rotationtherewith; and i. means for directing air dischargEd from said fan alongsaid fins.
 2. The sewing machine of claim 1 wherein said heatdissipating fins are an integral part of said bottom cover plate.
 3. Thesewing machine of claim 2 which further includes means for directing airdischarged from said fan over said top oil cover plate.
 4. The sewingmachine of claim 3 which further comprises air flow maintaining meansfor maintaining the air flow between said fins.
 5. The sewing machine ofclaim 4 wherein said means for directing air over said top oil coverplate includes means for restricting the air flow over said top oilcover plate such that less air flows over said top oil cover plate thanalong said fins.
 6. The sewing machine of claim 5 wherein said air flowmaintaining means is a plate mounted on the bottom of said fins.
 7. Thesewing machine of claim 5 wherein said air flow maintaining meanscomprises mounting means for maintaining the bottom of said finsadjacent to the surface on which said machine is mounted.
 8. The sewingmachine of claim 5 wherein said means for directing air oversaid top oilcover plate includes a top cover plate mounted on said frame above saidtop oil cover plate, defining a channel therebetween which is in fluidcommunication with said second chamber, said top plate including atleast one air discharge slot.
 9. A sewing machine which comprises: a. anup-standing frame defining a machine chamber and a second chamberadjacent to said machine chamber at one end of said machine, said secondchamber having an inlet port, a bottom discharge port and a topdischarge port; b. an operating head mounted on said frame at the otherend of said machine; c. a top oil cover plate mounted on the top of saidframe and sealing the top of said machine chamber; d. a top cover plate,having at least one air discharge slot, mounted on said frame over saidtop oil cover plate forming a sealed chamber with said top oil coverplate, said sealed chamber being in fluid communciation with said topdischarge port; e. a bottom cover plate mounted on said frame andsealing the bottom of said machine chamber; f. a plurality of heatdissipating fins mounted on the bottom of said bottom cover plate andextending longitudinally thereof; g. a drive shaft mounted on said framelongitudinally thereof, extending through said machine chamber and saidsecond chamber and adapted for external drive; h. means within saidmachine chamber for operatively connecting said drive shaft to saidoperating head; i. a ducted fan mounted within said second chamber andon said drive shaft for rotation therewith; j. means for directing airfrom said ducted fan, i. through said top port, and ii. through saidbottom port and along said fins.
 10. The sewing machine of claim 9wherein said means for discharging air from said fan through said topport comprises a fan duct having a slot in the top portion thereofadjacent said top discharge port.
 11. The sewing machine of claim 10wherein said means for directing air from said fan along said finscomprises: a. a plurality of downwardly facing louvers mounted on saidduct adjacent to the axial discharge of said fan; and b. a horizontallydisposed louver mounted on said frame adjacent to the bottom dischargeport.
 12. The sewing machine of claim 11 wherein said heat dissipatingfins are an integral part of said bottom cover plate.
 13. The sewingmachine of claim 12 which further comprises air flow maintaining meansfor maintaining the air flow between said fins.
 14. The sewing machineof claim 13 wherein said air flow maintaining means is a plate mountedon the bottom of said fins.
 15. The sewing machine of claim 13 whereinsaid air flow maintaining means comprises mounting means for maintainingthe bottom of said fins adjacent to the surface on which said machine ismounted.